So many responses over there, who is a troll and who isn't? It doesn't matter, there will be a ton of knock off MHL made after the phone is released. The people over there at Engadget forget how much MHL adapters cost when they first hit the market and there is no reason given but a video as mentioned in the comment section.
Maybe it's to support 1080p, maybe Samsung said hey we can make some extra money, maybe its to have a more secure hold to the phone, etc, etc. Won't stop the sale of the G3's in any way IMHO. Thanks for the link though OP.